Cell Organelles DSA (1)

Question 1

Lysosomal Sorting Pathway

Answer 1

1. Synthesis of lysosomal enzymes
2. Phosphorylation of lysosomal enzymes (M6P)**
3. Inter-golgi transporting vesicles
4. Binding of lysosomal enzymes to M6P receptor**
5. Clathrate coated transporting vesicle
6. The clathrin coat is lost. M6P receptor is recycled back to the Golgi and lysosomal enzymes are stored in a primary lysosome

Question 2

Primary and secondary lysosomes

Answer 2

Primary- storage site of lysosomal hydrolases; no digestive enzymes, homogenous, inactive enzymes

Secondary- engaged in a catalytic process; digestive enzymes, heterogenous, active enzymes

Question 3

Role of mtDNA mutations in disease

Answer 3

Mitochondrial disease are sometimes caused by mutations in the mtDNA that affect mitochondrial function

-other causes of mt disease are mutations in the genes of the nuclear DNA, whose gene products are imported into as mt proteins as well as acquired mt conditions

Question 4

Vesicle Transport Mechanisms

Answer 4

1. Clathrin-coated vesicles: transporting products from the Golgi to lysosomes or products from the exterior of the cell to lysosomes (like cholesterol)
2. COP-coated vesicles (coat protein): transporting products between the stacks of the Golgi (COP1-coated vesicles), and from the ER to the Golgi (COP2-coated vesicles)

Question 5

Familial Hypercholesterolemia

Answer 5

mechanism of cholesterol uptake is disrupted

• characterized by elevation of LDL, the predominant cholesterol transport protein in the plasma
• primary defect is mutation in gene encoding LDL receptor (incapable of binding LDL, bind at reduced capacity, bind normally but incapable of internalization); high levels of LDL lead to atherosclerotic plaques